bash$ tiagosh

When I was developing RNAT I needed to change one kernel function (ip_options_compile), but I didn’t want the users to recompile their kernels. So then I discovered here that it was possible to hijack a kernel function by using a kernel module, and it solved my problem for that moment.

To exemplify the hijacking process, the code below shows how to hijack sys_mkdir() system call, preventing any user from creating a directory.